Failure analysis - Root cause troubleshooting Being careful when troubleshooting pays off. The small circlip in this picture (circled) fell off a sealed mechanism, releasing a cam roller (squared). This clue could easily have been lost through the floor grating upon disassembly. On further analysis, this non-OEM part was shown to have failed in fatigue, thereby causing a control system instability that made a 12’ tall valve cycle without warning in a fraction of a second. Helping the end user revise purchasing procedures eliminated this problem globally. It also made people a feel a little bit safer walking around the large valve.